Pipe scarifying method and apparatus

ABSTRACT

An apparatus for hydrodemolishing the inside surfaces of an inclined pipe, particularly suited to contiguous pipe sections with access ports between the sections. The fluid supply hose is fed to the hydrodemolition rig inside the pipe from the same side as the winch that controls the movement of the rig. The rig is moved upstream in a scarifying pass, then downstream in a cleaning pass for each section and re-staged at each access port.

FIELD OF THE INVENTION

This invention relates to the hydrodemolition of the inside surfaces ofpipes, sometimes referred to as scarifying.

BACKGROUND OF THE INVENTION

The scarifying of the inside of in situ pipes requires the movement of ahydrodemolition apparatus (hereafter called a “rig”), comprising a highpressure nozzle assembly, along the length of the pipe.

According to a typical prior art approach illustrated in FIG. 1, the rig10 is attached to a hose 12 supplying high pressure fluid to the rigfrom the downstream end 14 of the pipe to be treated. The rig isattached to a winch cable 16 that extends from the rig to the upstreamend 18 of the pipe, where the winch 20 is located. The winch graduallydraws the rig from the downstream end to the upstream end of the pipe ina scarifying pass through the pipe to remove a layer 22, while the rignozzles 24 are operated to scarify the inside of the pipe. The fluidsupply hose 12 is fed from the opposed pump 26 side of the pipe, intothe pipe and to the rig from the downstream end of the pipe. As the rigis drawn by the winch, the rig in turn draws the hose into thedownstream end of the pipe.

Once the length of hose available on the pump side is exhausted, thehose will resist the forward movement of the rig in the pipe, causing itto stall in one spot while the nozzles are still operating. Once that isdetected, the rig is stopped and an additional length of hose isattached to the end of the first length of hose. Movement of the rig canthen be restarted to continue treatment of the inside of the pipe. Suchstalling of the rig results in a phenomenon sometimes referred to asbarbershop striping along the inside of the pipe. Personnel are oftenpositioned inside the pipe to try to manage the hose feed to the rig andto avoid barbershop striping.

It is also known to follow the scarifying pass with a cleaning passthrough the pipe using lower pressure fluid and consequently a differentnozzle assembly that is swapped out of the rig, or by using a differentrig entirely. The cleaning pass is typically accomplished usingessentially the same method as for the scarifying pass and prepares theinside of the pipe for further operations such as painting or coating.

Once the pipe has been completely treated, the other operations such aspainting or recoating the interior of the pipe can be completed,sometimes by a different crew or a different contractor.

The scarifying pass is performed in some cases by what is known as anultra-high pressure nozzle assembly, using pressure is in the range of40,000 psi. The cleaning pass is often performed using lower pressuresin the range of 10,000 to 20,000 psi.

The prior art suffers from certain deficiencies. The barbershop stripingproduces an inconsistent the treatment of the inside of the pipe.Personnel are required to assist and monitor the hose attachment to therig. In addition, the treatment process, including two passes throughthe pipe, is time consuming. When other contractors await access to thepipe on a usually tight timeline, processing time must be minimized.This becomes inconvenient when dealing with particularly long sectionsof pipe that may take many days or weeks to complete, if they may beaccomplished at all using the prior art approaches. Where a long lengthof pipe is involved, the drawing of the hose into the pipe by drawingthe rig attached to the hose can become particularly challenging,required very powerful winches.

In an alternative prior art approach, the rig may be installed at oneend of the pipe and may be towed by the hose itself which is drawn to ahose reel by a winch. However, this method of towing the rig tends tocause the rig to jerk inconsistently.

Another known approach is to have a tractor-driven rig inside the pipe.The rig progresses down the pipe while scarifying it, with the hosetrailing the rig. Typically personnel are present in the pipe toperiodically pull the hose in behind the rig. Alternatively the rig maybe equipped with a winch to draw the hose behind it. In such case,personnel is still required in the pipe to ensure that the connection ofthe hose to the rig is not compromised by the tension on the hose, andto avoid the hose causing the rig to stall.

The invention provides an apparatus and the method that represent animprovement over the prior art. The scarifying of the inside of the pipeis accomplished more efficiently and more quickly to free up access tothe treated section of pipe and the need for in-pipe personnel to dealwith the hose is avoided.

SUMMARY OF THE INVENTION

The present invention finds its most useful application where a longpipe needs to be treated in successive sections. This may be the casefor example where access ports are provided at intervals along the pipe.The access ports are designed for general maintenance of the pipes, butin the context of the invention may be used to define pipe sections tobe treated successively by providing an opportunity to periodicallyreinitialize the hydrodemolition operation, using the access ports asstaging areas to reconfigure the rig, the hose and the winches.

According to an embodiment of the invention, the hose for supplying highpressure fluid is fed to the rig from the same end of the pipe as thewinch. The starting configuration is to place the rig at a downstreamend of the pipe section to be treated. A winch cable is attached to therig and extends through the pipe section to the opposite, upstream endof the pipe section where it is attached to a winch. The fluid supplyhose is also attached to the rig and extends through the pipe section tothe upstream end, where it is attached to a powered hose reel.

In operation, the winch draws the rig through the pipe while the reelmotor reels the hose in at the same time. The speeds of the winch and ofthe hose reel are closely coordinated to ensure that the hose iswithdrawn from the pipe at the same rate as the rig.

As the rig is drawn from the downstream end to the upstream end in ascarifying pass, a nozzle assembly on the rig is operated to scarify theinside of the pipe section. Preferably the scarifying pass through thepipe section is performed using ultra high-pressure nozzles (in therange of 40,000 psi). The ultra-high pressure nozzle assembly ispreferably located on the downstream side of the rig.

Once the rig reaches the upstream end of the pipe section such that theentire section has been scarified, the ultra-high pressure hose isdisconnected from the rig and a high pressure hose used for a cleaningis attached to the rig. The rig and its attached hose are then migratedback through the same pipe section from the upstream end to thedownstream end. During the return pass, cleaning nozzles on the rig areoperated to clean the inside of the pipe section from the upstream endto the downstream end. Preferably high pressure nozzles in the range of10,000 to 20,000 psi are used for that “cleaning” pass. The highpressure nozzle assembly is mounted on the upstream end of the rig.

As a result of the foregoing process, where the pipe comprises a numberof contiguous sections to be treated, the rig ends up adjacent to thenext contiguous section of pipe to be treated. Where this coincides witha pipe access port, it enables the re-staging of the system for thefollowing section of pipe to be treated.

Using the access port, the winch cable and the hose are disconnectedfrom the rig, then each is drawn out of the pipe through the first,already treated, section. The winch and the hose reel are then moved tothe access port adjacent to the next section of pipe to be treated(where the rig is now located). The winch cable and an ultra-highpressure hose are attached through the access port to the rig. The rigis migrated down the second pipe section to a new starting point and theabove process is performed for that new section. As the rig is operatedin that section, the hose and the winch cable are fed through, or drawnfrom, as the case may be, the access port.

While the method of the invention is applicable to any pipe section, itis particularly convenient where the pipe section is at an incline. Inthat case, the rig, including the winch cable and the hose attached tothe rig, may be migrated down the pipe section by gravity. Where gravityassistance is not available, the rig and its attached winch cable andhose may be drawn through the pipe section to the downstream end by anadditional winch cable extended through the pipe section from thedownstream end. The second winch cable is then used to draw the rigthrough the pipe section to the downstream end to being the scarifyingpass. The same second winch cable is also used to later return the rigto the same downstream end of the section during the cleaning passthrough the pipe section.

By providing both an ultra-high pressure scarifying nozzle assembly anda high pressure cleaning nozzle assembly on the same rig, a synergy isachieved using the method of the invention. While the rig is migratedback to the downstream end of the pipe section, so as to be near thenext section of pipe to be treated, the high pressure cleaning nozzlesare actuated. As a result, as the rig is being migrated back to thestaging point for the next section of pipe, the system also performs thesecond or cleaning step of the treatment.

The inventors have found that a conventional hydraulic hose reel motordoes not provide sufficiently precise control to track the speed of therig in the pipe. Accordingly, an electric motor is used to power thehose reel.

The scarifying and cleaning nozzles are preferably angled slightlytoward the downstream end of the pipe section in order to propel anydebris and fluid downstream towards the downstream end of the pipe.

The foregoing may cover only some of the aspects of the invention. Otherand sometimes more particular aspects of the invention will beappreciated by reference to the following description of at least onepreferred mode for carrying out the invention in terms of one or moreexamples. The following mode(s) for carrying out the invention are not adefinition of the invention itself, but are only example(s) that embodythe inventive features of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

At least one mode for carrying out the invention in terms of one or moreexamples will be described by reference to the drawings thereof inwhich:

FIG. 1 is a side elevation showing a prior art approach two pipesscarifying;

FIG. 2 is a side elevation of an exemplary length of pipe to be treated;

FIG. 3 is a longitudinal cross-sectional view of a pipe section to betreated according to the method in using the apparatus of the invention;

FIG. 4 shows an embodiment of a method according to the inventioninvolving two winches;

FIG. 5 is a side elevation of the rig at a downstream end of a sectionof pipe prior to commencing a scarifying pass;

FIG. 6 is a side elevation of a pipe section with the rig at theupstream end of the section;

FIG. 7 is a side elevation showing a rig part way through a cleaningpass moving downstream of the pipe;

FIG. 8 is a side view of a rig according to an embodiment of theinvention;

FIG. 9 is a front view of an ultra-high pressure nozzle assemblyaccording to an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The rig according to an embodiment of the invention includes at one endof the rig an ultra-high pressure nozzle assembly for the scarifyingpass and a high pressure nozzle assembly for the cleaning pass, thelatter being located at the opposite end of the rig. Each nozzleassembly includes an axial hub and nozzle arms extending radially fromthe hub. Each nozzle arm terminates in a nozzle. The hub is rotatableabout a longitudinal axis of the rig so that the nozzles may treat acircumferential swath of the pipe section.

The ultra-high pressure nozzles are maintained at a close but controlledspacing from the inner surface of the pipe by means of rollers 57attached to the nozzle arms. The nozzle arms are also adapted to retracttoward the hub by means of hydraulic cylinders. The hydraulic pressureis adjusted so that in the event that the nozzles inadvertently enterinto contact with an obstruction or with the inner surface of the pipe,the arm can relatively easily yield and retract. The retractable armsalso facilitate the maintenance or replacement of the nozzles and theremovability of the rig through an access port.

The ultra-high pressure nozzles are further mounted on the ends of thenozzle arms using an articulation system enabling the nozzles toconically rotate about the end of the nozzle arm. The scarifying andcleaning nozzle assemblies include selected non-rotating nozzles thatare angled slightly off the radial axis toward the tangential directionto propel the nozzle assemblies to rotate about the hub.

Speed sensors are mounted on the rig to track the progress of the rigthrough the pipe and to enable close tracking and coordination of thespeed of the hose retraction by the powered hose reel. Forward andrearward cameras are mounted on the rig to enable the remote detectionof obstructions and to monitor the treatment of the pipe surface. If thetreatment is inadequate, the speed of the rig may be slowed down toenable more complete scarifying, or cleaning, as the case may be.

The rig includes a fluid inlet for connecting the ultra-high pressuresupply hose. That inlet is on the inboard side of the ultra-highpressure nozzle assembly. While the rig is performing the scarifyingpass, the ultra-high nozzles assembly is on the downstream end of therig, while the hose extends from the inboard inlet to the nozzleassembly, through the frame of the rig and past the cleaning nozzleassembly (which is not operated during the scarifying pass).

The high pressure cleaning nozzle assembly is located on the upstreamside of the rig. A fluid inlet for the high pressure cleaning hose ispreferably located in the middle of the hub on which the high pressurecleaning nozzle arms are located. The body of the hub rotates around theinlet. With that arrangement, the high pressure hose does not interferewith the spinning of the cleaning nozzles as the hose extends upstreamof the rig.

The winch is mounted on the same trailer that also carries the poweredhose reel.

FIG. 2 illustrates an exemplary length of pipe 30 to be treated. In theillustrated example, the pipe is a penstock pipe and overall length ofpipe to be treated is 2500 feet. Access ports 32-38 are provided atintervals along the pipe, for example, about every 600 feet. The accessports are used to conveniently define the pipe sections A-E. The accessports may be specifically created along the pipe to facilitate thehydrodemolition operation. The access ports may be approximately 2 feetin diameter. It may be contemplated, according to the invention, totreat each of contiguous pipe sections A, B, C, D and E as individualprocessing stages.

FIG. 3 is a longitudinal cross-sectional view of a pipe section A to betreated according to the method and using the apparatus of theinvention. Section A is shown as being on an incline. Also visible isthe upstream end 40 of the contiguous pipe section B, also at anincline. Access port 45 defines the transition between sections A and B.The hydrodemolition rig 42 is shown at the initial staging position atthe upstream end 43 of section A. A powered hose reel 46 is mounted on atrailer 48. A winch 50 is mounted on the same trailer. The winch cable52 is attached to the frame of the rig and the hose 54 is attached tothe ultra-high pressure fluid inlet 56 of the rig.

The first step in the method is to migrate the rig and the attachedwinch cable and hose to the downstream end 44 of section A, in thedirection of arrow 58. Where an incline as shown in FIG. 3 exists, therig may be migrated to the downstream end 44 by gravity, takingadvantage of the incline of the pipe section. The speed of the hose reel46 is controlled to track the rate of the descent of the rig along pipesection A. In the absence of any incline, a second winch cable 53 isattached to the rig from the end of the pipe section to draw the rig 42,the hose 54 and the winch cable 52 from the upstream end 43 to thedownstream end 44 of the section A, as shown in FIG. 4. The second winchcable may be fed into the pipe through an access port 45.

FIG. 5 shows the rig at the downstream end of section A, prior tocommencing the scarifying pass. In FIG. 5, for ease of drawing andsimplicity, sections A and B are shown without the incline. In order toperform the scarifying pass of section A, the winch 50 draws the rig 42from the downstream end 44 to the upstream end 43 of section A in thedirection of arrow 61. At the same time the powered hose reel 46 drawsthe hose 54 back onto the reel. During the scarifying pass, theultra-high pressure nozzle assembly 62 is operated by the ultra-highpressure fluid supply while the cleaning nozzle assembly 64 is notactuated, as it is not connected to any fluid supply.

The scarifying pass results in scarifying of the pipe section along thelength of section A to remove a layer 59. The rig ends up at theupstream end 43 of section A with the hose 54 substantially reeled in,but with layer 59 removed from the pipe section as shown in FIG. 6.

The ultra-high pressure hose 54 is disconnected from inlet 56. A highpressure (rather than an ultra-high pressure) supply hose 68, preferablyhoused on the same hose reel 46, is connected to the nose hub inlet 78at the upstream side of the cleaning nozzle assembly 64. The cleaningpass is then initiated by migrating the rig 42 back down the length ofsection A, in the direction shown by arrow 66. FIG. 7 shows the rig partway through the cleaning pass moving downstream of the pipe. If gravityis not available to move the rig downstream, a second winch cable isused, being fed from the downstream end of the pipe section throughaccess port 45 as was suggested by FIG. 4. Migration of the rigdownstream of the pipe continues until the rig reaches the access port45, i.e. the downstream end 44 of section A and the upstream end 40 ofsection B.

Once the rig has completed the downstream cleaning pass and is locatedadjacent the access port 45, the access port 45 is then used to gainaccess to the rig to disconnect the high pressure hose 68 and the winchcable 52, both of which are then drawn back to the hose reel 46 and tothe winch 50 respectively. The trailer 48 carrying the hose reel and thewinch is then brought to the access port 45 at which point the winchcable 52 and the ultra-high pressure hose 54 are reconnected to the rigthrough the access port. The rig is then ready to be migrated from theupstream end 40 of section B to the downstream end of section B,essentially repeating the operation described above but for section B.This process may continue through an indefinite number of pipe sections,using the access ports to stage the operation for each new section ofpipe.

It is expected that a given section can be treated using the approachand apparatus of the invention in about half the time it would takeaccording to the prior art.

FIG. 8 shows of the apparatus according to an embodiment of theinvention. An ultra-high pressure nozzle assembly 62 is provided at afirst end of the rig and a high-pressure nozzle assembly 64 is providedat opposed end of the rig. Each assembly comprises nozzle arms 70extending radially from a rotatable hub 72. A regulator is provided inthe rig to regulate the speed of rotation of the nozzle arms 70. As isknown, some of the nozzle arms carry a plurality of ultra-high pressurenozzles that are mounted in a rotatable housing at the end of the nozzlearm to allow them to rotate in an arc about the end of the nozzle arm.As a result, as the rig progresses, a circular swath of high-pressurefluid is directed to the surface of the pipe so that as the nozzle armsrotate about the hub, a circumferential swath about the pipe is treated.

FIG. 9 is a front view of the ultra-high pressure nozzle assembly 62.Selected ones 63, 65 of the nozzles are oriented slightly toward thetangential direction of the pipe in order to propel the radial arms torotate about the hub. This avoids the need for powered actuation of thenozzle assembly.

The rig includes an inboard ultra-high pressure hose inlet 74 forsupplying the ultra-high pressure nozzle assembly 62. Since the rig willbe moving in the direction shown by arrow 76 when an ultra-high pressurehose is attached to the inlet 74, the only nozzle assembly that will beoperating and rotating will be the ultra-high nozzle assembly 62, whilethe high pressure nozzle assembly 74 will be stationary. As a result,the ultra-high pressure hose 54 may be threaded between the stationarynozzle arms of the high pressure nozzle assembly 64.

The high pressure hose inlet 78 if provided outboard of the rig on thenose 80 of the hub 72. Hub 72 rotates around the stationary nose 80. Bymeans of this arrangement, when the rig is travelling upstream in thedirection of arrow 82 the high pressure hose 68 does not interfere withthe rotation of the high pressure nozzle assembly 64. A hook 84 isprovided for attaching the winch cable that attaches to the upstream endof the rig 42.

As no personnel are contemplated in the pipe during the scarifying orcleaning operations, cameras 86, 88, 90 and 92 are provided to allowremote viewing of the operations. Speed sensors 94 are also provided toenable accurate tracking by the powered hose reel of the speed of therig 42.

In the foregoing description, exemplary modes for carrying out theinvention in terms of examples have been described. However, the scopeof the claims should not be limited by those examples, but should begiven the broadest interpretation consistent with the description as awhole. The specification and drawings are, accordingly, to be regardedin an illustrative rather than a restrictive sense.

1. A method for hydrodemolition of the inside of an inclined pipesection comprising: a. installing a rig within a lower, downstreamportion of said pipe section, said rig comprising a nozzle assembly; b.attaching a winch cable to said rig, said cable extending within saidpipe section from a higher, upstream portion of said pipe section tosaid rig; c. extending a first water hose from a hose reel at saidupstream portion to said rig; d. using a winch to draw said rig upstreamthrough said pipe section while simultaneously reeling in said firsthose on said hose reel at substantially the same speeds, while saidnozzle assembly operates to hydrodemolish the inside of said pipesection, until said rig reaches such upstream portion; and, e. migratingsaid rig within said pipe section from said upstream portion to saiddownstream portion while said nozzle assembly cleans the inside of saidpipe section.
 2. A method for hydrodemolition of the inside of aninclined pipe comprising contiguous sections, at least one pipe accessport being provided between said contiguous sections, comprising: a.installing a rig within a lower, downstream portion of a first pipesection and adjacent said at least one pipe access port, said rigcomprising a nozzle assembly; b. attaching a winch cable to said rig,said cable extending within said first pipe section from higher,upstream portion of said first pipe section to said rig; c. extending afirst water hose from a hose reel at said upstream portion within saidfirst pipe section to said rig; d. using a winch to draw said rigupstream from said downstream portion through said first pipe section ina scarifying pass while simultaneously reeling in said first hose onsaid hose reel at substantially the same speeds, and while said nozzleassembly operates to hydrodemolish the inside of said first pipesection, until said rig reaches said upstream portion; e. migrating saidrig within said first pipe section from said upstream portion to saiddownstream portion in a cleaning pass while said nozzle assembly cleansthe inside of said first pipe section; f. accessing said rig throughsaid at least one pipe access port to disconnect said winch cable andany hose from said rig; g. drawing said winch cable and said any hoseupstream to said upstream portion and out of said first pipe section; h.introducing said winch cable and said first hose through said at leastone pipe access port and attaching said winch cable and said first hoseto said rig; i. migrating said rig downstream to a downstream positionin relation to a second pipe section, said second pipe section beingcontiguous to and downstream of said first pipe section; j. using saidwinch to draw said rig upstream from said downstream position throughsaid second pipe section in a scarifying pass while simultaneouslyreeling in said first hose on said hose reel at substantially the samespeeds, and while said nozzle assembly operates to hydrodemolish theinside of said second pipe section, until said rig reaches the upstreamportion of said second pipe section; and, k. migrating said rig withinsaid second pipe section from said upstream portion of said second pipesection to said downstream portion of said second pipe section in acleaning pass while said nozzle assembly cleans the inside of saidsecond pipe section.
 3. The method of claim 1 further comprising, priorto step e, a step of disconnecting said first hose from said rig andconnecting a second hose to said rig, said second hose supplying lowerpressure water to said nozzle assembly than said first hose.
 4. Themethod of claim 2 wherein said first hose is an ultra-high pressure hoseand said rig comprises a fluid inlet for connecting said ultra-highpressure supply hose, said fluid inlet being on an inboard side of saidnozzle assembly and at a downstream end of said rig, said hose extendingfrom said inlet to said nozzle assembly through a frame of said rig andpast a cleaning nozzle assembly located on an upstream portion of saidrig.
 5. The method of claim 1 or claim 2 wherein said downstream portionof said pipe section is a downstream end of said pipe section and saidupstream portion of said pipe section is an upstream end of said pipesection.
 6. The method of claim 1 wherein said step of migratingcomprises migrating using gravity.
 7. The method of claim 2 wherein saidsteps of migrating comprise migrating using gravity.
 8. The method ofclaim 1 or claim 2 wherein said hose reel is actuated by an electricmotor.
 9. A method for hydrodemolishing the inside of a pipe comprisingcontiguous sections, at least one pipe access port being providedbetween said contiguous sections, comprising: a. installing a rig withina downstream end of a first pipe section and adjacent said at least onepipe access port, said rig comprising a nozzle assembly; b. attaching awinch cable to said rig, said cable extending within said first pipesection from an upstream end of said first pipe section to said rig; c.extending a first water hose from a hose reel at said upstream endwithin said first pipe section to said rig; d. using a winch to drawsaid rig upstream from said downstream end through said first pipesection in a scarifying pass while simultaneously reeling in said firsthose on said hose reel at substantially the same speeds, and while saidnozzle assembly operates to hydrodemolish the inside of said first pipesection, until said rig reaches said upstream end; e. migrating said rigwithin said first pipe section from said upstream end to said downstreamend in a cleaning pass while said nozzle assembly cleans the inside ofsaid first pipe section; f. accessing said rig through said at least onepipe access port to disconnect said winch cable and any hose from saidrig; g. drawing said winch cable and said any hose upstream to saidupstream end and out of said first pipe section; h. introducing saidwinch cable and said first hose through said at least one pipe accessport and attaching said winch cable and said first hose to said rig; i.migrating said rig downstream to a downstream position in relation to asecond pipe section, said second pipe section being contiguous to anddownstream of said first pipe section; j. using said winch to draw saidrig upstream from said downstream position through said second pipesection in a scarifying pass while simultaneously reeling in said firsthose on said hose reel at substantially the same speeds, and while saidnozzle assembly operates to hydrodemolish the inside of said second pipesection, until said rig reaches the upstream portion of said second pipesection; and, k. migrating said rig within said second pipe section fromsaid upstream portion of said second pipe section to said downstreamportion of said second pipe section in a cleaning pass while said nozzleassembly cleans the inside of said second pipe section.